package com.zt.common.utils;

import cn.hutool.core.codec.Base64;
import cn.hutool.http.HttpUtil;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.springframework.core.env.Environment;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.AlgorithmParameters;
import java.security.Security;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class WechatUtil {

    public static JSONObject getSessionKeyOrOpenId(String code){
        Environment environment = ApplicationContextUtil.get(Environment.class);
        String requestUrl = "https://api.weixin.qq.com/sns/jscode2session";
        Map<String,Object> requestUrlParam = new HashMap<>();
        requestUrlParam.put("appid",environment.getProperty("wechat.appid"));
        requestUrlParam.put("secret",environment.getProperty("wechat.secret"));
        requestUrlParam.put("js_code",code);
        requestUrlParam.put("grant_type","authorization_code");
//        HttpUtil.post(requestUrl,requestUrlParam);
        return JSON.parseObject(HttpUtil.post(requestUrl,requestUrlParam));
    }

    public static JSONObject getUserInfo(String encryptedData,String sessionKey,String iv){
        //被加密数据
        byte[] dataByte = Base64.decode(encryptedData);

        //加密密钥
        byte[] keyByte = Base64.decode(sessionKey);

        //偏移量
        byte[] ivByte = Base64.decode(iv);

        try {
            int base = 16;
            // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
            if (keyByte.length % base != 0){
                int groups = keyByte.length / base + (keyByte.length % base != 0?1:0);
                byte[] temp = new byte[groups * base];
                Arrays.fill(temp,(byte)0);
                System.arraycopy(keyByte,0,temp,0,keyByte.length);
                keyByte = temp;
            }

            //初始化
            Security.addProvider(new BouncyCastleProvider());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
            parameters.init(new IvParameterSpec(ivByte));
            cipher.init(Cipher.DECRYPT_MODE,spec,parameters);
            byte[] resultByte = cipher.doFinal(dataByte);
            if (resultByte != null && resultByte.length > 0){
                String result = new String(resultByte, "UTF-8");
                return JSON.parseObject(result);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;

    }
}
